Well, at least the 3132+ date for Dark Age could be fixed, because that is definitely wrong, even for product eras.
The HPG grid collapsed in 3132, which is when the Dark Age starts.
That the Republican sub-era for MUL goes backwards is of no consequence, just as the "Age of War" era for Star League goes backwards.
All this was considered when the Eras were made and they were made, on purpose, the way they are on that page.